Question { HCL, 11831 }

where the generated jsp source file are stored?

Answer

C:\Program Files\Apache Software Foundation\Tomcat 5.5\work\Catalina\localhost\webApplicationName\org\apache\jsp\xxx.java

Question { ABC, 7967 }

I have 2 objects inside one object(vector). how can i
serialize one of them. I dont want to serialize the second one

Answer

this answer is not correct. bcz java compiler will throw an error-illegal declaration of statement.check it out.

I think we will go for Externalizable interface. But the problem is how write the code inside writeExternal() & readExternal() methods

Question { Lionbridge, 6930 }

explain session tracking. why we used it

Answer

session tracking is the process of keeping session data(i.e-the data exchanged between server & client as part of httpRequest)to use these data in further pages.

If the server supports stateless protocol like:http then the server can't store the session data exchanged between server & client in earlier pages.if we use stateful protocol it will reduce performance as it takes more memory & more time.
So we can use session tracking/session handling techniques,like:
url rewritting
hidden form fields
cookies
session managed by cookies
session managed by url rewritting

Question { 5316 }

difference between String a; and String a=new String();?
y do v need to assign memory to the variable?

Answer

String a;
jvm creates a reference & allocates memory for storing hashcode value

String a=new String();
jvm creates a object to String class in heap memory & returns the unique hexadecimal equivalent of that memory location which is stored in reference variable a as hashcode.

We dont need to assign memory to variable.because in java memory management is taken care by jvm automatically.Programmer need not worried about memory allocation issue.But yes jvm allocates memory for variable to store hashcode, if it is a referenced variable.If it is primitive type variable then jvm will not allocate extra memory for that variable.Because primitive types stored in object & there is memory allocated for object by jvm.

Question { 15930 }

Can I have constructor in Interface?

Answer

no we can't have constructor in an interface, why bcz constructor is used to initialize the instance variable stored in an object. Constructor is called concurrently while creating object. We can't create object to interface & also we can't provide instance variable to interface. So we can't use constructor in an interface